How Trees Grow and Toward Which Side They Grow Most
Grafted shoots outgrow their branch; boughs seek air and thrive on their moist underside
This leaf from Book Six of the Trattato, on trees, continues a discussion of nourishment: a little shoot grafted onto a cut branch grows thicker than the branch that feeds it, and shield-grafting many buds onto a cut trunk quickly builds up thickness. A chapter on the growth of trees explains that boughs grow away from the plant's interior because every branch seeks the air and flees the shade. Because rainwater and night dew gather on the underside of branches, that lower part stays moister and better nourished, so the branches grow more there. A further chapter, on which branches grow most in a year, begins at the foot of the page; the sheet is a clean Melzi copy without drawings.
On this page
Grafting: a shoot outgrows the branch that feeds it
If a branch is cut and one of its own little shoots is grafted onto it, the shoot in time grows much thicker than the branch nourishing it, because the vital spirits rush to the injured place. Shield-grafting many buds in a circle onto a cut trunk builds up more thickness in a single year than the whole face of the cut trunk.
Boughs flee shade and grow on their moist underside
The branchings of the larger boughs do not grow toward the middle of the plant, because every branch naturally seeks the air and flees the shade. The rainwater and the dew that multiplies by night gather on the underside of the branches, keeping that lower part moister and better nourished, so the branches grow more there.